Ocean Acidification May Cause Major Food Web Changes with Warming Temperatures

First Posted: Jul 22, 2015 08:35 AM EDT

As temperatures heat up, ocean acidification is on the rise. Now, scientists have found that ocean acidification may cause some major changes in the ocean's food chain due to its effect on phytoplankton communities.

Phytoplankton's role in the marine food chain is significantly. These microscopic marine plants form the foundation of the marine food web and regulate key biogeochemical processes. In a balanced ecosystem, phytoplankton provide food for a wide range of sea creatures, including whales, shrimp, snails and jellyfish.

"Because phytoplankton types are not physiologically interchangeable, changing which species are most common in a community can impact the cycling of elements, the flow of nutrients and energy through the marine food web," said Jeffrey Morris, one of the researchers, in a news release. "The implications could be substantial."

Already, the world's oceans have absorbed about 30 percent of fossil fuel carbon emission caused by human activity, resulting in a significant decrease in surface ocean pH. Concerns over the impacts of ocean acidification in marine life have led to a number of studies examining the response of marine life to ocean acidification.

In this latest study, the researchers analyzed published experimental data that assessed growth rates of different phytoplankton populations under elevated acidity levels. The data showed a wide variety of responses. Then, the scientists studied the data in the context of a global marine ecosystem to explore how marine phytoplankton communities might be impacted over the course of the 21^st century from 2000 to 2100.

So what did they find? It turns out that different types of phytoplankton responded to the alterations in different ways. What was clear, though, was that the ecosystem changed dramatically.

"One of the striking things about this work is it shows that all phytoplankton groups will be affected by ocean acidification-not just the groups that make calcium carbonate shells, like those you see on corals, which is what researchers have traditionally assumed," said Morris. "We now know that the structure of phytoplankton populations will morph in the future. Further research will help us determine how that shift will alter other marine life that depend on phytoplankton for survival, and the marine ecosystem in its entirety."

The findings are published in the journal Nature Climate Change.